Data on HIV cases reported in 33 U.S. states with HIV reporting indicate the burden of HIV/AIDS is most concentrated in the African American population compared to other racial/ethnic groups. Of the 49,704 African American males diagnosed with HIV between 2001 and 2004, 54% of these cases were among men who have sex with men (MSM). In Los Angeles County (LAC), the proportion of HIV/AIDS cases among African American males attributable to male-to-male sexual transmission is even greater (75%). In the absence of an effective vaccine, behavioral interventions represent one of the few methods for reducing high HIV incidence rates among African American MSM (AAMSM). While a number of individual- and group-level HIV interventions have been created by and for a variety of AAMSM organizations across the U.S., evaluation data to document the effectiveness of these programs are practically non-existent. Given the conspicuous absence of both 1) evidence-based HIV interventions and 2) best practices outcome evaluations of existing AAMSM programs, our collaborative team intends to address a glaring research gap by implementing a scientifically rigorous evaluation of an insufficiently evaluated homegrown HIV prevention program developed for AAMSM ages 18-29 years. This application responds directly to the funding opportunity announcement RFA-PS-09-007 by proposing a systematic program evaluation of In The Meantime Men's Group's (ITMT) locally developed MyLife MyStyle small-group intervention. MyLife MyStyle was designed by AAMSM in Los Angeles County in 2005-2006 to address the crucial HIV prevention needs of 18- to 29-year-old AAMSM, a population experiencing the highest rate of HIV incidence in the U.S. In the MyLife MyStyle Evaluation Project, the collaborative team will test the hypothesis that participants of the MyLife MyStyle program will report at least a 15% absolute decrease in frequency of unprotected anal sex with male partners at three months post-intervention. To test our research hypothesis and to understand critical elements of an intervention designed for young AAMSM at risk of HIV acquisition and transmission, we have identified the following Specific Aims for the 5-year project period: 1) Implement a randomized controlled trial for a minimum of 300 AAMSM, ages 18-29 years, to test the effectiveness of MyLife MyStyle to reduce unprotected anal sex (UAS) with male partners at three months post-intervention compared to a wait-list control condition; 2) Conduct a comprehensive program evaluation to identify intervention elements associated with program success, such as: a) intervention components, processes, and characteristics; b) recruitment and retention strategies; c) requirements of the organization's infrastructure necessary to deliver the intervention; and d) a cost-effectiveness analysis.